Electron discharge device of the magnetron type



W W49. W. c. BROWN ETAL, ZAQQQ ELECTRON DISCHARGE DEVICE OF THEMAGNETRON TYPE Filed July 23, 1946 2 Sheets-Sheet l @pt R949. C V N ETEAWEW ELECTRON" DISCHARGE DEVICE OF THE MAGNETRON TYPE Filed July 23,1946 2 Sheets-Sheet 2 F/GZ,

Patented Sept. 6, 1949 ELECTRON DISCHARGE DEVICE OF THE MAGNETRON TYPEWilliam G. Brown, Lincoln, and Erich Nevin Kather, South Lincoln, Mass.,assignors to Raytheon Manufacturing Company, Newton, Mass., acorporation of Delaware Application Jilly 23, 1946, Serial No. 685,579

3 Claims. 1

This invention relates to electron-discharge devices, and moreparticularly to electron-discharge devices of the type commonly known asmultipleanode m'agnetrons.

Devices of the general character to which reference has been made haveheretofore been of practical value only when used at relatively highfrequencies, for example, at about 3000 megacycles, or higher. At lowerfrequencies, the size of the device became prohibitive, the constructionthereof became unduly complex, and, if the device was intended to handleappreciable power, an elaborate cooling system became necessary.

It is, therefore, the main object of the present invention to eliminatethe foregoing disadvantages, and provide a multiple-anode magnetron, theconstruction of which is practical for use at lower frequencies, forexample, in the region of 100 megacycles.

It is another object of the present invention to reduce the complexitiesof a relatively low-frequency magnetron by so constructing the same thatthe tuning circuit and magnetic field-generating means thereof arelocated outside the envelope of the device.

It is still another object of the present invention to provide amultiple-anode magnetron, the construction of which is simplified byeliminatil'lg the need for pole pieces.

It is a further object of the present invention to provide amultiple-anode magnetron with a simplified cooling system and yet beable to handle power of appreciable magnitude.

These and other objects of the present invention, which will become moreapparent as the detailed description thereof progresses, are attained,briefly, in the following manner:

The device of the present invention comprises an envelope, made,preferably, of glass, in which there is centrally mounted a cathode.Concentrically disposed about the cathode, in spaced relationshipthereto, is a plurality of anode members, each of said members includingan electronreceiving element, and a fluid-receiving element in physicalcontact with said electron-receiving element over an appreciable areathereof. At one end thereof, alternate electron-receiving elements areelectrically tied together, intervening electron-receiving elements,likewise, being electrically tied together, but at the ends oppositesaid first-named ends. The fluid-receiving elements partially extendexteriorly of the envelope, and are electrically interconnected by afluid-receiving, electrically-conductive header havin inlet and outletports for a cooling fluid, such as water.

The header is divided into incomin and outgoing compartments, the formercommunicating with the fluid-receiving elements of the anode members tosupply cooling fluid to such members, and the latter communicating withopen-ended pipes disposed within said fluid-receiving elements to enablethe removal of the cooling fluid after the same has circulated throughthe anode members. Thus, the anode members, in addition to being cooled,are so electrically shorted that, when of proper physical dimensions,each pair of adjacent members, together with that portion of the headerlying therebetween, constitute a shorted, quarter-wave transmission lineadapted to resonate at the frequency desired of the output of thedevice. The device is completed by providing, exteriorly thereof, andsurrounding the envelope, a coil which, when energized, establishes amagnetic field in the space between the cathode and anode members, in adirection perpendicular to the electron path between said cathode andanode members.

In the accompanying specification there shall be described, and in theannexed drawings shown, an illustrative embodiment of theelectron-discharge devices of the present invention. It is, however, tobe clearly understood that the present invention is not to be limited tothe details herein shown and described for purposes of illustrationonly, inasmuch as changes therein may be made without the exercise ofinvention, and within the true spirit and scope of the claims heretoappended.

In said drawings,

Fig. 1 is a longitudinal sectional view taken substantially through thecenter of an electrondischarge device assembled in accordance with thepresent invention; and

Fig. 2 is a transverse sectional view taken on line 2-2 of Fig. 1.

Referring now more in detail to the aforesaid illustrative embodiment ofthe present invention, with particular reference to the drawingsillustrating the same, the numeral l0 designates a generally cylindricalenvelope having a relatively deep, dome-like upper wall II and arelatively shallow, dome-like lower wall f2, said envelope being made,preferably, of glass.

The end wall H is provided with an inwardlydirected,centrally-apert'ured protuberance [3 to which is sealed a ferrule I4made, preferably, of the material known as Kovar, said ferrule beingadapted to support a cathode assembly l5 axially within the envelope it.

While not limited thereto, the cathode assembly I may be constructedsubstantially in accordance with the disclosure in the copendingapplication of Benjamin B. Butler entitled Electrodes. serial No.676,550, filed June 13, 1946, and now U. S. Patent No. 2,468,736, issuedMay 3, 1949. As here shown, said cathode assembly comprises a rod Itmade, preferably, of molybdenum, said rod being supported from a Kovarferrule l1 sealed to a glass ring l8, in turn, sealed to a Kovar ring l9secured to a sleeve 20, said sleeve also bein made of molybdenum andbeing secured to the ferrule M. The inner end of the rod I6 carries amolybdenum ring 2|, and between said ring 2| and the inner end of thesleeve there is supported a coiled electron-emissive filament 22 made,preferably, of relatively heavy tungsten. The cathode assembly iscompleted by a pair of shields 2'3 and 24 carried, respectively, by thesleeve 20 and the ring 2!,

Spaced from the cathode assembly l5, and disposed concentricallythereabout, is a plurality of anode members 25. Each anode member 25comprises an electron-receiving block 26 made, preferably, of highlyconductive material, such as copper, said. block being provided, nearits outer wall, with a longitudinal bore receptive of the upper end of atubular, fluid-receivin element 21, likewise, made, preferably, ofcopper. All of the fluid-receiving elements 21 extend through the bottomwall l2 of the envelope Ill, .being supported by Kovar ferrules 28sealed to outwardlydirected protuberances 29 formed in said bottom walll2.- The upper ends of the fluid-receiving elements 21 are closed, as at30, and the lower ends thereof are open, and telescopically engaged intubes 3| fixed in the upper wall of a fluidreceiving header 32 made,preferably, of copper, whereby all of the anode members 25 becomeelectrically interconnected exteriorly of the envelope H]. Thefluid-receiving elements 21 and associated tubes 3! are so adjusted withrespect to each other that each pair of adjacent anode members 25,together with that portion of the header 32 interconnecting the same,constitute a shorted transmission-line section whose electrical lengthis equal to that of a quarter-wave at the frequency desired of theoutput of the device.

In order to suppress spurious oscillations, the upper ends of alternateelectron-receiving blocks 26 are electrically tied together by aconducting strap 33, the lower ends of intervening electron receivingblocks 26, likewise, being electrically tied together by a conductingstrap 3d.

The header 32 is divided, by a baille 35, into an incoming fluidcompartment 36, provided with a cooling fluid inlet pipe 31 andcommunicating with the open lower ends of the tubes 3|, and an outgoingfluid compartment 38, provided with a cooling fluid outlet pipe 39 andcommunicating with the open lower ends of pipes 40 supported in thebaffle 35 and extending upwardly into the fluid-receiving elements 21,whereby a circulation of cooling fluid may be maintained to and from theanode members 25.

The envelope It may be surrounded by a coil 4| which, when suitablyenergized, establishes a magnetic field in the space between the cathodeassembly l5 and the anode members 25, in a direction perpendicular tothe electron path between said cathode assembly and said anode members.

The device is completed by any appropriate means for extractingoscillatory energy therefrom, for example, a loop 42 magneticallycoupled members mounted within said envelope, spaced relationship tosaid cathode, and parto the tubes 3| of two adjacent anode members 25,said loop having one end connected to a central conductor 43 of acoaxial transmission line, and its other end connected to a pipe 44constituting the outer conductor of said coaxial transmission line.

This completes the description of the aforesaid illustrative embodimentof the present invention. It will be noted from all of the foregoingthat the present invention provides a multiple-anode magnetron capableof handling appreciable power at relatively low frequencies, forexample, frequencies in the region of megacycles. It will further benoted that by reason of the construction of the present invention, thesize thereof may be held within practicable limits, and the complexitiesheretofore associated with relatively low-frequency magnetrons areeliminated, due, particularly, to the location of the tuning elementsand the magnetic field generating means exteriorly of the device.Finally, it will be noted that although the magnetrons of the presentinvention are intended to handle appreciable power, the cooling systemthereof is relatively simple.

Other objects and advantages of the present invention will readily occurto those skilled in the art to which the same relates.

What is claimed is:

1. An electron-discharge device comprising: a hermetically sealedenvelope; a cathode mounted within said envelope; a plurality of anodemembers mounted within said envelope, in spaced relationship to saidcathode; each of said anode members including outer and inner tubularelements; and a fluid-receiving, electrically-conductive headerelectrically interconnecting said anode members whereby each pair ofadjacent anode members, together with that portion of said header lyingtherebetween, constitute a shorted transmission-line section adapted toresonate at the frequency desired of the output of the device; saidheader including a housin divided into fluid-incoming and fluidoutgoingcompartments communicating, respec tively, with the outer and innertubular elements of each of said anode members.

2. An electron-discharge device comprising: a hermetically sealedenvelope; a cathode mounted within said envelope; a plurality of anodetially extending exteriorly of said envelope; each of said anode membersincluding coaxially-disposed conduits; and a fluid-receiving,electrically-conductive header electrically interconnecting said anodemembers exteriorly of said envelope whereby each pair of adjacent anodemembers, together with that portion of said header lying therebetween,constitute a shorted transmission line section adapted to resonate atthe frequency desired of the output of the device; said header includinga housing divided into fluid-incoming and fluid-outgoing compartmentscommunicating, respectively with the coaxial conduits of each of saidanode members.

3. An electron-discharge device comprising: a hermetically sealedenvelope; a cathode mounted within said envelope; a plurality of anodemembers mounted within said envelope, in spaced relationship to saidcathode, and partially extending exteriorly of said envelope; each ofsaid anode members including outer and inner tubular elements; afluid-receiving, electrically-conductive header electrically intercontheouter and inner tubular elements of each of 10 ,19

said anode members; and an output coupling device disposed adjacent saidanode members in the vicinity of said header.

WILLIAM 0. BROWN. ERICH NEVIN KATHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,054,126 Hollmann Sept. 15, 19362,189,501 Helbig Feb. 6, 1940 Blewett Sept. 30, 1947 FOREIGN PATENTSNumber Country Date 443,077 Great Britain Feb. 20, 1936

